gh-121842: Improve coverage of PyBytes_FromStringAndSize (#121843)

Author: sobolevn

Lib/test/test_capi/test_bytes.py

@@ -53,6 +53,8 @@ def test_fromstringandsize(self):
         self.assertEqual(fromstringandsize(b'abc'), b'abc')
         self.assertEqual(fromstringandsize(b'abc', 2), b'ab')
         self.assertEqual(fromstringandsize(b'abc\0def'), b'abc\0def')
+        self.assertEqual(fromstringandsize(b'a'), b'a')
+        self.assertEqual(fromstringandsize(b'a', 1), b'a')
         self.assertEqual(fromstringandsize(b'', 0), b'')
         self.assertEqual(fromstringandsize(NULL, 0), b'')
         self.assertEqual(len(fromstringandsize(NULL, 3)), 3)